1. Field of Invention
The present invention relates to jack stabilizing devices commonly found on recreational vehicles such as motor homes and trailers. Recreational vehicles or RV's typically have vertically extending jacks attached to the frame near the corners of the vehicle. When parked, these jacks are extended to the ground and provide a means for leveling the RV in addition to supporting the weight of the RV. This support prevents vertical movement of the vehicle as the occupants of the RV move about it. While offering a great deal of weight capacity, most RV jacks provide little resistance to side to side movement caused by wind or people moving inside the RV. A mechanical jack stabilizer that effectively limits lateral movement between the lower portion of the jack and the RV frame is achieved by this invention utilizing a four link mechanism as described herein.
2. Prior Art
Previously, strut type devices have been employed to stop lateral movement in RV jacks. They fall into two basic designs. The first consists of a first hollow tube telescopically fitted inside a second hollow tube. The non-telescoped ends of each tube are pivotally attached to the frame of the trailer and the foot of the jack. The result is a tube that can shorten or elongate to accommodate the changing distance from the RV frame to the foot of the jack as the jack is extended or retracted. Once the jack is lowered to its operating height, a locking nut is tightened between the two telescoped sections, fixing the length of the two telescoped sections and the strut assembly provides lateral stability to the jack. The second design employs a single piece strut pivotally attached at one end to the foot of the jack. The opposite end of the strut slides through a clamping device attached to the frame of the RV. The clamp is left loose until the jack is lowered to its operating height. The clamping device is then tightened and the jack is laterally stabilized. Both of these types of stabilizers work well, but have the disadvantage of having to be manually tightened after the jacks are extended, and then loosened prior to the jacks being retracted. The locking nuts or clamps are located underneath the RV. Depending on the conditions where the RV is parked, such as mud or wet grass, or for physically challenged people who may not have the flexibility to get under their RV, tightening and loosening the jack stabilizers can be quite inconvenient.
Previously, four link devices have been designed to achieve straight line support of movement over short distances. These types of devices required three or more planes of operation making them bulky. In order to achieve any significant length of straight line operation, these devices operate on both sides of a mounting link and have a center of stroke, or neutral point in their stroke where the device may actually track on to a curved path or continue in a straight line path depending on how they are loaded. This type of device is not suited to the objects of the current invention.